Lubricants



yatented inn. 6, 1942 George lii. McNulty and mm C. Zimmer; :Union, N. 3., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 5, 1939,

' Serial No. 307,588

18 Claims.

This invention relates to improved lubricants and more particularly to oil and grease lubricating compositions intended for lubricating moving metal parts which contact each other under high pressures,.such as high film strength'oils for bearings and engines, extreme pressure lubricants forgears, and cutting oils as used for machining various metals, etc.

In the lubrication of hypoid or other gear various chlorinated or halogenated materials are used alone or incombination with sulfur compounds, and the chlorine or halogen compounds and sometimes phosphorous compounds are very effective in carrying the high loads demanded of extreme pressure lubricants, but they have one disadvantage, namely, the tendency to rust the gear surfaces which are being lubricated. They also cause corrosion and staining of ferrous and copper-bearing alloys used in bearings, bushings, pistons, etc. Also sulfur alone or in the presence of chlorine as present in cutting fluids, usually causes a black stain such as copper sulfide on copper alloys.

Ithasnow been found and is a primary object of the present invention that this undesirable corrosion and staining of metals can be prevented by adding to the high film strength or extreme pressure lubricant, a small amount of an oil-soluble organic amine having various properties as will be described later.

The invention will be better understood from the following examples:

Example 1 An E. P. (extreme pressure). lubricant was made of the following composition:

Per cent Sulfurized non-corrosive fatty oil base (10% sulfur) 10 Chlorinated wax (40% chlorine) '7 Mineral oi 83 This composition, which contains 2.8% chlorine based on the total lubricant, was found to corrode steel under the following conditions:

(A) 25 ccs. of the above oil and 5 ccs. of water were put in a 50 cc. beaker in which there was a polished steel rod; this steel rod showed rusting in 16 hours at a temperature of 180 F.

(B) A sample of the same oil was tested on the Almen test machine for minutes with a load of four weights, then the test oil and test pieces were placed in a bottle and moist air passed through for 24 hours; the steel became corroded.

Now by adding from .05% to 0.2% of phenyl ethanolamine to the same lubricating composition and repeating the test,- it was found that the rusting tendencies'oi the steel were reduced to only a slight stain and by still further increasing the concentration of the amine to 0.3% even the staining tendencies were eliminated, giving a bright clean metal.

Example 2' A small amount of trie'thanolamine was added to the same lubricating composition and found to be eliective in eliminating corrosion and stain- Example 3 Small amounts of cyclohexylamine, triamylamine and dicyclohexylamine were similarly tested and found to be excellent in their efiectiveness in eliminating corrosion and staining.

. Example 4 A cutting oil was prepared having the following composition:

. I Per cent Mineral oil S. U. seconds at 100 F.) 99.2 Elementary sulfur 0.8

This cutting oil is suitable for machining bronze metal parts but it causes darkening of the bronze.

0.2% of phenyl ethanolamine was added to the same cutting oil and was found to eflectively eliminate the staining tendencies of the sulfur bearing lubricant when heated for 100 hours at 200 F. in the presence of bronze.

Example 5 Example 6 A lubricant containing sulfur or chlorine or both treated with a phosphorous-bearing oil-soluble base towhich trlamylamine has been added is non-reactive to ferrous and cuprous alloys.

Example 7 The polymerization product formed by reacting sodium polysulfide with a halogenated hydrocarbon following blending with mineral oil and containing a product such as cyclohexylamine, dicyclohexylamine, or triethanolamine does not corrode or stain steel.

pressure lubricant prepared by Example 8 A cutting oil containing dissolved sulfur and chlorine or other halogen, which can be used on cutting machines containing bronze gibs and used for cutting operations on ferrous or cuprous alloys, causes staining or rusting or corrosion, but this is prevented by adding a small amount of an amine such as phenylethanol amine, hexyl amine or amyl cyclohexyl amine.

As the oil-soluble organic base, the amines and substituted amines arepreferred, particularly those having an ionization constant greater than about 1 10 or having a pKH value above about 7.0. (The higher the numerical figure for the value pKH, the more basic is the compound.)

The amines to be used are preferably selected from the group consisting of mono-, (11-, and trialkyl and cyclo-alkyl amines, dialkyl aryl amines. and hydroxy, aryl and 1 double bond (meaning corresponding oleflnic) derivatives thereof. Usually the amines to be used should have an ionization constant between the approximate limits of 1X 10 and 1X or a pH range of 7.0-11.1, and preferably an ionization constant between .lxlO- and 1 l0 or a pH of 9.0-11.0, and should preferably also have a boiling point between the approximate limits of 150 and 400 C. at atmospheric pressure. Phenyl ethanolamine has a pKH value of 7.35 and a boiling point of 286 C. and dicyclohexylamine has a pKH value of 10.74. and a boiling point of 115 C. (at 8 m. 121.). Both of these amines were shown above to be particularly satisfactory, both in laboratory cor- The term pKH is a reciprocal measurement of the hydrogen ion concentration determined after a partial nciltrnliznflon, as described in J. A. C. 8., vol. 54. p. 8469 et seq. (1932).

Now, although itis believed that the degree of ionization or the basicity of the amines or other compounds-used is an important factor in the mechanism of the operation of the invention, it is apparently not the sole controlling factor because, for instance, aryl amines such as aniline, toluidine, naphthyl amine, and the like, are not satisfactory and yet aniline has a pKH value of 7.80, which is higher than 7.35, the pKH value of phenyl ethanol amine which is satisfactory. On the other hand, higher alkylated aryl amines appear to be suitable. such as those having at least 3 aliphatic carbon atoms, but preferably about 4 to 6 carbon atoms such as tertiary amyl aniline, tC5H11.CcH4NH2. Therefore, although it is not intended that the invention be unnecessarily limited by any theories as to the mechanism or chemistry or other phenomena involved in the operation of the invention, it is believed that in some way the valuable characteristics of the invention are related partly to the inherent chemical structure of the amines or other compounds in question and to their relative basicity or degree of ionization.

The following tables list a number of amines falling within the broader scope of this invention, showing their pKH values, although a few do not fall within the preferred range of 0.-11.0 pKH.

2,2es,eos

Taste L-Alkyl amines KH R D 5 ENE: RINK RiN 10.04 10.71 9.80 10.67 10.88 10.74 10.58 10.01 10.06 10.63 11.05 10. B1 11. 31 9. 03 10.42 10.82 10.32 10.66 10.40 10.64 11.18 10.64 11.) ISO-Conn. 10.61

TABLE 2.--Benzulamines pKH CsI-hCHzNI-Iz 9.34 CsHsCHzNHCH: 9.58 CeHsCHzNHCaHs 9.68 CoHsCHsN(CH3)a 1. 8.93 CsHsCI-I:N(C:Hu)a 9.48

Tssu: 3.-Phenyl alkyl amines.

pKH pKH Benzylamine 0.34 N-methylbenrylsmlne.. 9.68 Beta-phenylothylaminc.. 9.83 N-methyl'beta-phenyl- -Phenyl-n-gropylamine. 10.!) ethylemine 10.14 8-Phenyl-nuty amine 10.40 N-methyl -phenyl-ns-Phenyl-n-athyleniihe... 10.49 prop lam no 10.88

N-me hyl-l-phenyl-nbutylamlne 10.75

TABLE 4.--Alkul piperidines DKH I pKH Pl icli 11.13 lth l-2' tb li ril-e t ylpi pseridine 10.40 ziln euu i ufu i rlu 10.88 l-n-butylpiperidine 10.42 l-n-butyl-2-methyl-- 4Q'2-methylpiperidlns 10.98 piperldine 10.72

TABLE 5.--Ethanolamines pKH Ethanolamine 9.44 to Diethanolamine 8.88 Triethanolamine 7.77

TABLI: 6.-Phenul uuanidines pKH 5o Guanldine 13.65 Phenylguanidine 10.77 Diphenylguanidine 10.12 Triphenylguanidine 9.10

TABLI: 7.Miscellaneous amines in order accord- Di-isopropylamhie 11.05

Some other amines which can, be used include:

as well as cyclo-alkylamines in which one or 20 more of the hydrogens on the cyclic nucleus is replaced by alkyl groups.

Some of the hydroxy, 'aryl and 1 double bond or olefinic derivatives of the alkyl and cycloalkyl amines include the following:

Mono-cetyl diethanol amine Phenyl ethanol amine (the phenyl group being attached to the ethanol group but not directly to the nitrogen) Di-cyclo hexylene amine Mono-oleyl amine Di-oleyl amine Cyclohexyl oleyl amine Diethyl benzyl amine 5 a -Mono and dialkyl mono aryl amines e. g. N-diethyl phenyl amine, N-octadecyl benzyl ammonium hydroxide, dibenzyloctadecyl sulfonium hydroxide, etc., and their salts or 4 soaps may also be used.

Generally, the amount of the oil-soluble organic base to be used should be between the approximate limits of 0.01% and 1.0% depending upon the type and the amount of chlorine and sulfur or other active and corrosive load-carrying elementsin the lubricant but generally an amount between the approximate limits of 0.05% and 0.5% will sufiice.

The invention is particularly applicable to extreme pressure lubricants containing corrosive chlorine compounds, for instance, chlorinated aliphatic or aromatic hydrocarbons such as chlorinated paraffin wax, kerosene, aromatic, petroleum, or coal tar solvents and derivatives in which a portion of the chlorine has been replaced by sulfur. The amount of chlorine, especially the active chlorine, to be used will, of course, depend upon the severity of the conditions under which the lubricant is to be used but 05 will generally vary between the approximate limits of 5% to 50% in the chlorinated organic compounds or between the approximate limits of .05% and 10% based on the total weight of lubricant (exclusive of any water which may be used as in the preparation of water-soluble type cutting oil). I

In preparing extreme pressure lubricants of the halogen type, it is frequently desirable to incorporate sulfur compounds especially to increase Y the stability of the lubricantat high temperature and for this purpose a sulfurized fatty or mineral oil or a sulfur compound such as an organic sulfide, mercaptan, dior poly-sulfides, xanthates, xanthogen sulfides, thio carbonates, etc., may be used in which generally from about 1% to 30% of sulfur is incorporated in the active or combined state. Based on the total weight I of lubricant, the proportion of sulfur should normally be between the of about 0.2% and 10%. a

Instead of using separate chlorine compounds and sulfur compounds, it is possible to use single materials in which both sulfur and halogen have been incorporated by-treatment with a sulfur halide or by reacting the halogen compound with aminorganic sulfide, poly-sulfide, thio carbonate or xanthate.

Although the mechanism and the operation of the present invention are not thoroughly understood and it is not desired to be limited to any particular theory as to the operation thereof, it

is believed that the active chlorine compounds present in the extreme pressure lubricant, are

capable of carrying very high loads between metal surfaces by means of the formation of microscopic films of metal halides such as ferrous. or

ferric chloride which prevent metal to metal contact and resultant welding and scoring. These films, particularly in the presence of moisture which is almost always present in gear cases tend to hydrolyze into metal oxides and hydrochloric acid. Also the chlorine compounds in the lubricant itself tend to hydrolyze with the liberation of hydrochloric acid (H01) and this acid in turn attacks the metal surface because iron and steel and various alloys in general are quite susceptible to attack or corrosion by hydrochloric acid and other strong halogen acids. on the other hand, in lubricants containing a substantial amount of active sulfur, the latter, particularly in the presence of moisture and at elevated temperature and pressures produced between gear teeth or overa long period of time, tends to be converted into hydrogen sulfide and the latter tends to react with the metal to produce the corresponding metal sulfldes which are generally black, such as iron and copper sulfides.

The oil-soluble organic amines of this inven tlon are believed to have .some effect in preventing hydrolysis of the metal chloride films and they also apparently neutralize any nascent hydrochloric acid which may tend to form, and these organic amines act diiferently in oil than they do in aqueous media and have some unexpected ability to alter the chemical reactions which take place when the lubricant is subjected to extreme pressure conditions, permitting the desired film formation and lubrication under high pressures without substantial corrosion of the adjacent metal surfaces.

If desired, other known addition agents or lubricants may be incorporated in the lubricant prepared according to the present invention; for instance, fatty, fatty acid or naphthenic acid soaps, esters, thickeners such as polyisobutylene having a molecular weight above 1,000, pour dewell as hetero-cyclo-aliphatic amines, such as the alkyl piperidines disclosed in Table 4.

It is not intended that this invention be limited to any of the particular examples which have been given for illustration only, nor by any of the theories as to the operation or the invention but only by the appended claims in which it is intended to claim all novelty inherent in the invention as broadly as the prior art permits.

We claim:

1. A lubricant comprising an active halogen in a form normally corrosive to metals but capable of greatly increasing the load-carrying capacity of the lubricant and also comprising a, small amount of an oil-soluble cycle-aliphatic amine having a pKH value greater than about 7.0.

2. An extreme pressure lubricant comprising a major proportion of a mineral 011 base stock. a substantial amount of an organic compound containing a substantial amount of halogen in an active condition, and a small amount of an oilsoluble cyclo-alkylamine having a pKH value between the approximate limits of about 9.0 and 11.1.

3. An extreme pressure lubricant comprising a' major proportion of a mineral 011 base stock, a substantial amount of an organic compound containing a substantial amount of chlorine and sulfur in an active condition. and a small amount of an oil-soluble cyclo-alkylamine having a'pKH value between the approximate limits of 8.0 and 11.0.

a. Lubricant according to claim 3 in which the amount of amine present is enough to substantially prevent corrosion of metals coming in contact therewith.

5. Lubricant according to claim 3 in which the amine has a boiling point between the approximate limits of 150 to 400 C.

6. Lubricant according to claim 3 in which the amine contains at least one cyclo-hexyl group.

7. Lubricant according to claim 3 in which 0.01 to 1.0% of dicyclohexylamine is used.

8. An extreme. pressure lubricant comprising a major proportion of a mineral oil base stock, a substantial amount of an organic compound containing a substantial amount of chlorine and phosphorus in an active condition, and a small amount or an oil-soluble cycle-aliphatic amine having a pH value greater than about 7.0.

9. An extreme pressure lubricant comprising a major proportion of a mineral oil base stock, a substantial amount of an organic compound containing a substantial amount of halogen, sulfur and phosphorus in an active condition, and a small amount of an oil-soluble cycle-aliphatic amine having a pH value greater than about 7.0-.

10. Method of preparing substantially noncorrosir'e extreme pressure lubricants which comiii prises adding a small amount of dicyclohexylamine into a normally corrosive extreme pressure lubricating composition containing halogen and sulfur.

11. The method of reducing the corrosive tendencies of extreme pressure lubricating compositions containing an element selected from the group consisting of chlorine and sulfur, which comprises incorporating therein a small amount of an oil-soluble cycle-aliphatic amine having a pH value greater than about 7.0.

12. An extreme pressure lubricant comprising a major proportion of mineral oil base stock, a substantial amount of a compound containing halogen in an active condition, and a small amount of a cycle-aliphatic amine having attached to the nitrogen atom one hydrogen atom and at least one cycle-aliphatic hydrocarbon group.

13. Lubricant according to claim 12 in which the amine has the general formula NHRz, in which R represents a cyclo-alkyl group.

14. Lubricant according to claim 12 in which the amine has the general formula NHRR', ,in which R represents a cyclo-allryl group and R represents an aliphatic hydrocarbon group.

15. An extreme pressure lubricant comprising a major proportion of mineral oil bas stock, a substantial amount oiv constituents containing chlorine and sulfur in an active condition, said active chlorine being present in an amo nt of about .05% to 10% based on the total lubricant, and said active sulfur being present in an amount of about 0.2% to 10% based on the total lubricant and said lubricant also containing about .01% to 1.0% of a cyclo-alkylamine having the property of preventing corrosion and staining of metals coming in contact therewith, due to said active chlorine and sulfur.

16. Lubricant-according to claim 15 in which the amine is dicyclohexylamine.

17. An extreme pressure lubricant comprising a major proportion of a mineral 011 base stock, a substantial amount of an organic compound containing chlorine in active condition, the

amount of chlorine present being at least about 2.8% by weight of the total lubricant, and a small amount of an oil-soluble cyclo-aliphatic amine having a pKH value greater than about 7.0.

18. An extreme pressure lubricant comprising about 83% of mineral lubricating oil, about 10% of sulfurized non-corrosive fatty oil base containing 10% of sulfur, and about 7% of chicrinated wax containing about 40% of chlorine,

to which lubricant has been added about 0.2% of di-cyclohexylamine.

GEORGE M. MCNULTY. JOHN C. ZIMMER. 

